How to Calculate Nernst Equation
What is Nernst Equation?
The Nernst equation calculates the electrode potential of an electrochemical cell under non-standard conditions (non-unit concentrations). E = E° − (RT/nF) × ln(Q). At 25°C it simplifies to E = E° − (0.0592/n) × log(Q).
Step-by-Step Guide
- 1E = E° − (0.0592/n) × log(Q) at 25°C
- 2n = moles of electrons transferred
- 3Q = reaction quotient (product of concentrations)
- 4E > 0 means cell is spontaneous; E = 0 means equilibrium
Worked Examples
Input
E°=1.10V (Zn-Cu cell) · n=2 · Q=0.001
Result
E = 1.10 − (0.0592/2)×log(0.001) = 1.10+0.089 = 1.189V
Dilute reactant → higher cell potential
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